number-theory / Extremal Divisibility

Erdős Problem #709

How long must an interval be to contain distinct representatives $x_i$, with $a_i \mid x_i$, for every $n$-element set of moduli $A = \{a_1, \dots, a_n\}$?

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number-theoryJul 13, 2026Significance 10/100Registry: lean verified

Erdős Problem #709

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upper bound improved to f(n) ≤ 14n^{3/7} with an explicit logarithmic lower bound; matching bounds remain open

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How long must an interval be to contain distinct representatives $x_i$, with $a_i \mid x_i$, for every $n$-element set of moduli $A = \{a_1, \dots, a_n\}$?

upper bound improved to f(n) ≤ 14n^{3/7} with an explicit logarithmic lower bound; matching bounds remain open

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